Solid state lighting (“SSL”) devices are used in a wide variety of products and applications. For example, mobile phones, personal digital assistants (“PDAs”), digital cameras, MP3 players, and other portable electronic devices utilize SSL devices for backlighting. SSL devices are also used for signage, indoor lighting, outdoor lighting, and other types of general illumination. SSL devices generally use light emitting diodes (“LEDs”), organic light emitting diodes (“OLEDs”), and/or polymer light emitting diodes (“PLEDs”) as sources of illumination, rather than electrical filaments, plasma, or gas. FIG. 1A is a cross-sectional view of a conventional SSL device 10a with lateral contacts. As shown in FIG. 1A, the SSL device 10a includes a substrate 20 carrying an LED structure 11 having an active region 14, e.g., containing gallium nitride/indium gallium nitride (GaN/InGaN) multiple quantum wells (“MQWs”), positioned between N-type GaN 15 and P-type GaN 16. The SSL device 10a also includes a first contact 17 on the P-type GaN 16 and a second contact 19 on the N-type GaN 15. The first contact 17 typically includes a transparent and conductive material (e.g., indium tin oxide (“ITO”)) to allow light to escape from the LED structure 11. In operation, electrical power is provided to the SSL device 10a via the contacts 17, 19, causing the active region 14 to emit light.
FIG. 1B is a cross-sectional view of another conventional LED device 10b in which the first and second contacts 17 and 19 are opposite each other, e.g., in a vertical rather than lateral configuration. During formation of the LED device 10b, a growth substrate, similar to the substrate 20 shown in FIG. 1A, initially carries an N-type GaN 15, an active region 14 and a P-type GaN 16. The first contact 17 is disposed on the P-type GaN 16, and a carrier 21 is attached to the first contact 17. The substrate is removed, allowing the second contact 19 to be disposed on the N-type GaN 15. The structure is then inverted to produce the orientation shown in FIG. 1B. In the LED device 10b, the first contact 17 typically includes a reflective and conductive material (e.g., silver or aluminum) to direct light toward the N-type GaN 15.
One aspect of the LEDs shown in FIGS. 1A and 1B is that an electrostatic discharge (“ESD”) event can cause catastrophic damage to the LED, and render the LED inoperable. Accordingly, it is desirable to reduce the effects of ESD events. However, conventional approaches for mitigating the effects of ESD typically include connecting a protection diode to the SST device, which requires additional connection steps and can compromise the electrical integrity of the resulting structure. Another aspect of the LEDs shown in FIGS. 1A and 1B is that the performance levels of the devices may vary due to internal heating, drive current, device age and/or environmental effects. Accordingly, there remains a need for reliably and cost-effectively manufacturing LEDs with suitable protection against ESD and other performance-degrading factors.